The rise of the electric resistivity ρ as a function of the temperature follows a logarithmic curve in a certain temperature range. PTC-resistors may be produced in the form of disks with a circular, quadratic or rectangular shape.
Such PTC-resistors are suitable for a wide range of applications, in particular including overcurrent protection devices, switches and additionally as heaters.
PTC-resistors can be fabricated by dry pressing of a granulate. The variety of possible shapes of such PTC-resistors with a base body being manufactured by dry pressing is strongly restricted to very simple geometric structures such as disks like those mentioned above.